base: FAI -> Fedora + rpm-ostree
base: Drop GPG signing with transient key

Other people don't have my one off key which creates pain.

In the future the trees generated from official infrastructure should
be signed.
base: Switch to rawhide only

Drop the debug kernel, because it's also a not-in-official-Fedora
package.

Also, we no longer need my COPR since

https://github.com/projectatomic/rpm-ostree/commit/827e711eb74135f075f02f5c44685e4e35c1a8b1

\o/